Study on the Tolerance of Silkworm (Bombyx mori L.) Hybrids to Unfavorable Conditions of Rearing

Y. LAZAROV, P. TZENOV and Y. NACHEVA

Sericultural Experimental Station, BG-3000 Vratza, Bulgaria

Abstract

LAZAROV, Y., P. TZENOV and Y. NACHEVA, 2000. Study on the tolerance of silkworm (Bombyx mori L.) hybrids to unfavorable conditions of rearing. Bulg. J. Agric. Sci., 6: 589-592

The tolerance of 12 silkworm moth hybrids to unfavorable conditions of rearing was studied. The hybrids were tested under a standard and provocation regimes during instars IV and V, namely: temperature 30-310C, relative air humidity 60-70%, feeding space and ration reduced by 50% and aeration available only upon entering and exiting the silkworm rearing room for the feeding.
The provocation regime of rearing applied allows for hybrid differentiation in view of their tolerance to unfavorable conditions of rearing. Under the provocation rearing regime, the hybrid with the highest pupation rate exceeds that with the lowest 7.22 times, the superiority for the index of cocoon yield per box of silkworm eggs being 3.55 times.
In the conditions of the provocation rearing regime, the hybrid KK x Vesletz 2 and the opposite cross showed the highest pupation rate and cocoon yield per box of silkworm eggs 47.59% and 5.41%, respectively.

Key words: silkworm moth (B. mori L.), unfavorable conditions, tolerance, hybrids